There's a lot of change that has come with AX7 (Dynamics 365 for Finance and Operations), ranging from plentiful technical changes but also the way implementations are being run. Any large change is usually disruptive to existing users of the product, and it takes time to learn the changes and get used to them. There's been plenty of changes in some major releases of AX, but one type of change has now come around that we haven't had to deal with before: rethinking how we design customizations.

Now, I'm not talking about technology or code but rather DESIGN of customizations. As I've stated before, the extension paradigms in AX7 weren't invented for the sake of new technology, but as an enabler to get to quicker and easier updates and upgrades. What's largely overlooked in discussions is that in many cases this requires not just using extensions in your code, but also to design your customization to allow for easy updates. And as a result, this means that some customizations cannot be ported from over-layering into extensions just like that. But that doesn't mean you can't give the user the easy button she was asking for.
Now that our version 8.0 of the Application is released, the era of NO over-layering is upon us. And to illustrate the points from above, I'd like to share an example of a customization I dealt with at a customer who came from AX2012 with plenty of existing code, and much of it "intrusive" (as in, not-easily-upgradable because it changes existing code). When the platform packages were originally sealed in Platform Update 2, this particular customization posed a problem for this customer. As opposed to being just one customer asking for a specific hook point (delegates, etc.) they need for one customization, we went back to the drawing board to discuss the original requirement and see if we could reimplement it in a "softer" way.

Here's the customization. The customer in question sometimes has large purchase orders and department heads need to approve specific lines that apply to their departments. They typically filter the lines to check what applies to them, and then just want to approve the whole lot with a click of a button as opposed to each line individually. They want to do this straight from the purchase order screen where they're reviewing all the details. In AX2012, a customization was made to the workflow framework (red flag) that adds an option to the approval ribbon. Instead of just cancel/reject/approve, a new option was added: approve all lines. It would then approve all the lines in this P.O. assigned to the user approving. The framework is locked in platform, so this change could not stay and couldn't be done with extensions...
Although perhaps not as nice as the original, the solution was relatively simple. Instead of changing the framework itself, we made a customization on the approval step. When the user approves a line, we can prompt her that there are other lines and ask if she wants to approve all. This has several clear advantages: no more framework change (which may have to be merged/changed on next upgrade), plus we use the superficial public API to approve an item (as opposed to adding logic inside the approvals itself). So when the framework changes its logic or adds new features, our customizations will just use advantage of those automatically.

This goes back to a principle I always like to adhere to in AX customizations as much as possible: don't change the process, but automate existing processes. When a request comes in, I like to ask the simple question: how would you do this manually, regardless of how convoluted that process would be? For example, the customer needs an extra financial transaction to happen somehow somewhere in existing logic. Question: how would you do this manually? It makes them think about the process. Typically they would create some journal somewhere with references to the original transaction. Ok, so can we now just automate creating/posting that journal and make sure it can be tied back? This opposed to creating an individual extra ledger transactions inside the original process, which would be very intrusive, error-prone and would have to be reviewed with each upgrade to make sure we're in line with the original code or changes to the transactions frameworks.

I realize there will be examples where even this doesn't apply. But I challenge you to ask the question whether that means the customization is really a good idea at all, and how it would be impacted if the Application Suite changed some of the details of the implementation. Customers upgrading from previous releases will face these dilemmas for sure, but now is the time to rethink the design, or perhaps even question the existence of the customization entirely.
In other cases, some of these intrusive customizations are done to correct strange or incorrect behavior in the application. Most of us have been there: some XPO sitting on a local share which you can re-use at every customer. And therein lies another mindset change: please file support requests! Don't ask for hookpoints so you can correct wrong behavior, rather ask Microsoft to fix the behavior! I realize and know from experience that the "by design" answer gets very tiring very quickly, but things are changing rapidly and this is one way everyone can improve the product and reduce friction. Your fellow AX users will thank you, and your organizations/customers will thank you on the next upgrade.